PowerPointPrsentation

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Satmode Link Budget Analysis Tool
Presented by Hervé Martial Peuengueu
Kamgang Universtiy of Saarland
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Contents Part I Overview 1-
Introduction 2- System Architecture 3-
Satmode Return Channel Protocol Stack 4- Access
Strategy Part II - The Tool 5- GUI Flow
Chart 6- Scenario Example 7- Live Simulation
of a given scenario Part III Conclusion
Discussion 8- Conclusion 9- Discussion
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Part I - Overview
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1. Introduction
1.1. What is Satmode? SATMODE is a low data rate
return channel via satellite with the purpose of
connecting STBs with each other and with
interactive service infrastructures in real time
and all the time. 1.2. Goal This work aims the
implementation of a tool, which allows the user
to plan, evaluate and assess the possible
scenarios for large deployment of terminals in
Europe. This means that the optimum transponder
operating point, the corresponding transponder
attenuator value (flux control attenuator), the
sensitivity of the whole system vis-à-vis some
given parameters (e.g. pointing loss, rain
attenuation), the link margin, the corresponding
link availability should be computed by the
tool.
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2. System Architecture
The system architecture is constituted by the
sending terminals, the geostationary satellite
(ASTRA 1H , 192 East) and the Hub. Each terminal
has an antenna, an interactive low noise block
and a set top box. The used modem layer
corresponds to the Satmode standard . The
terminals transmit data to the satellite with a
frequency of 30 GHz in the Ka-band. In the
satellite, the received data are then
retransmitted to the Hub station located in
Betzdorf at the frequency of 18.8 GHz. Data
processing is operated by the Hub, then the
processed data are sent to the terminals with a
frequency of 30 GHz via satellite. Whenever the
satellite receives data from Hub, retransmits it
to the terminals at a frequency of 18.8 GHz.
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2. System Architecture

• The transponder itself is transparent, this means
  that it does not perform data Proces-
• sing on board.
• The main task of the satellite transponder is to
  receive in a given frequency band,
• amplify and retransmit in another frequency band.
• Ka-band is the band of choice, because of it is
  barely used currently for satellite
• systems and is available. Also the antenna gain
  at Ka-band is higher and permits the
• use of smaller dishes.
• By using different frequency bands for sending
  and receiving the same antenna can be
• used for both sending and receiving via the
  satellite.
• The low noise block (LNB) has to be replaced by a
  so called interactive LNB (iLNB)
• that permits to transmit at Ka-band while
  receiving in Ku-band.
• The used modulation scheme is GMSK because of its
  constant envelope that permits
• the realization of cheap and saturated
  electronics.

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2. System Architecture
ASTRA 1H Satellite operating at 192 East
Ku-Band
Atmospheric Attenuations
Ku-Band
Atmospheric Attenuations
Ka-Band
Downlink
Ka-Band
Uplink
Hub Station Betzdorf -Lattitude49.69
-Longitude6.33
Interactive Terminals
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3. Satmode Return Channel Protocol Stack
Support network applications i.e. interactive
application software and runtime environment.
Application
Application programming interface
Digital Storage Media Command and Control
DSM-CC User to
Transporting application layer messages between
the client and the server sides of an application
HTTP
UNO-RPC
Service specific
Universal Networked Object - Remote Procedure
Call
UDP
TCP
Internet Protocol
Routing datagrams from one user(host) to another
Satmode Network
LLC deals with error detection, flow control, and
frame formats.
Satmode LLC
main work move entire frames from one network
element to an adjacent one.
Satmode Datalink Layer
Satmode SAR
SAR splits large messages into smaller datagrams
before transmitting it to the medium and
reassembles incoming datagrams before
transmitting it to the higher layers
Satmode MAC
MAC controls the access to the communication
channel
Satmode physical layer
moves the individual bits (within a frame) from
one node to the other
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4. Access Strategy

• The system is based on a multi-frequency TDMA
  model using slotted ALOHA
• as access strategy.
• ALOHA obtain reasonnable throughput only at low
  loads and they offer little in
• terms of performance guarantees.
• In the satellite environment with long wireless
  delays, detecting collisions adds considerable
• overhead, therefore slotted ALOHA is much more
  likely to be implemented.

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4. Access Strategy
Used Time Slot

• MF-TDMA

Unused Time Slot
Frequency
f6
f5
f4
f3
f2
f1
Time
To
T1
T2
T3
T4
T5
T6
T7
T8
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Part II - The Tool
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4. GUI Flow Chart
4.1. The GUI
Requested Energy per bit power over noise ratio
Power to uplink noise floor ratio
IBO of the existing adjacent system in
transponder
G/T Contour defining The maximum of the Population
Defining coverage area
Scenario specification (terminals distribution)
Limit of negative margin used only to
filter the graphical results
Value of the variance of the emitted amplified
power
Plot pie chart (do_adj_CI, up_noise_power,
up_noide floor, Cadjac, up_adj_CI, npr)
Plot Pie chart (Thermal CNo downlink, Total
Interferences CNo , Thermal CNo uplink)
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4. GUI Flowchart
Start

4.2. Flowchart The figure beside describe the
flowchart of the whole software. The two next
figures are describing the flowchart by a
statistical analysis and by uplink and downlink
computation
Geo p2p
Geographical or P2P analysis
Statistical analysis
Generate Beam Characteristics According to
Scenario
Generate Beam Characteristics According to
Scenario
Compute Uplink
Compute Uplink
Compute Downlink
Compute Downlink
Compute margin
Compute margin
Determine max. Availability.
Compute statistics
Plot Cno inter.
Calculate Attenuation For 99.000.0599.90
Determine corr. Margin
Plot statistics
Determine Population
yes
P2p?
Differential Analysis
Plot geo. Result (atten. Margin, pop, Footprint,
avaiability)
yes
no
no
Geo?
Determine IBOopt
Plot IBO
Determine dominating Noise factor (uplink,
downlink intermod.)
Plot corr. figure
Plot ACI
yes
no
Text output
P2p?
End
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4. GUI Flowchart
Flowchart of the uplink and downlink functions
Flowchart of the statistical analysis
Load ACI table
Load ESA table
Start
Generate new terminals (positions) and Beam
characteristics according to scenario For
sim11sim_total
For symb_rate 2.33, 4.65, 9.27, 18.39, 36.22,
70.26, 132.43 kbps
Compute ACI
Compute downlink attenuations
Compute Uplink
Load ESA table
Compute margin for all terminal
Compute Downlink
Compute downlink power to noise ratio
yes
no
Margingt0?
Compute uplink attenuations
Compute Margin
Link closure
Link non-closure
Return downlink data
Compute uplink noise to power ratio
yes
Symb_rate132.54kbps?
Simsim_total?
no
no
Return uplink data IBO
yes
End
Downlink
Uplink
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1. What is the maximum bitrate required to
achieve 99.90 of availability?
6. Scenario Example

• Considering the following scenario
• with a total number of terminals of
• 30.000 spreaded according to the
• table beside over Poland.
• With the Tool, the following
• 4 questions will be answered

2. What will be the bitrate distribution over the
terminal population under clear sky?
3. What impact does the pointing accuracy have?
This means the sensitivity on the link margin.
4. What is the recommended satellite operating
point and the corresponding flux control
attenuator value?
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6. Scenario example

• 6.1. Maximum bitrate required to achieve 99.90
  of availability

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6. Scenario example

• The pictures represented in the previous slide
  show that a data rate of
• 2.33 kbps is required to achieve an
  availability of 99.90 , if one wants to cover
  the entire Poland area.
• To have more infornmation on the availability by
  the considered scenario a statistical analysis
  has to be performed.
• This statistical analysis allow the user to
  determine the bitrate distribution under a
  considered scenario and by a given availabillity.

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6. Scenario example

• 6.2. Bitrate distribution

The figure besides shows that by a wanted
availability of 99.9 , 49.77 of the terminals
are transmitting with a rate of 4.65 kbps and
46.22 with 9.27 kbps. This mean that the
required bitrate to achieve 99.9 of availability
can be set to 4.65 kbps. In this case only 1.43
of the terminals can not achieve the required
availability.
PS The above graph is the result of 3000
simulations of the considered scenario
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6. Scenario example

• 6.3. Birate distribution under clear
• sky conditions
• Under clear sky conditions the
• atmospheruic attenuation decrease
• considerably and the bitrate distribution
• looks like represented in the figure
• beside.
• 9.44 od the terminals are trabsmitting
• with a rate of 132.54 kbps
• 73.93 with a rate of 70.26 kbps and
• 16.68 with a 36.22 kbps.
• In this case the required datarate should
• be set to 36.22 for all terminals.

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6. Scenario example

• 6.4. Impact of the pointing loss (4.65 kbps)

The effect of pointing loss on the margin
increases as the datarate increase Example A
Terminal located in Warsaw
The effect of the pointing loss on the margin for
some given locations in Poland is very important.
Threfore this should not be neglected.
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6. Scenario example

• 6.5. Recommended satellite operating point
• Used datarate 4.65 kbps

The optimal IBO computed by the tool for a
geographical ananlysis corresponds to 7.3664
dB. The corresponding attenuator setting is then
6.9579 dB
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6. Scenario example

• 6.6 Other Aspects
• Population Statistics

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6. Scenario example

• Carrier Center Spacing
• Effect of CSS by an Terminal located in Warsaw

Uplink, Downlink thermal noise and interferences
by CSS1
Uplink, Downlink thermal noise and interferences
by CSS0.7
By reducing CSS it follows an increases of the
amount of interferences and principaly an
increase of the adjacent carriers interferences
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6. Scenario example
Interferences by CSS1
Interferences by CSS0.7
As mentioned in the previous slide the figures
aboves show that ACI increasea significantly.
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6. Scenario example
Optimum IBO for a Terminal in Warsaw by a CSS1
Optimum IBO for a Terminal in Warsaw by a CSS0.7
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7. Live Simulation of a given scenario

• Proposed Scenario
• Beam France
• Total Number of terminals 100.000

• Geographical Analysis (2.33 kbps, 4.65, ...)
• Point-to-Point Analysis for Paris
• Statistical Analysis

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Part III Conclusion Discussion
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8. Conclusion

• pointing losses have important negative impacts
  on the link quality
• An use of low CCS has as result the increase of
  the Interferences
• In the practice a lower CCS as the symbol rate
  can be used without strong signal quality
  degradation considering that all carriers are not
  always transmitting at the same time.
• The simulation results show that under fully
  loaded conditions the downlink can indeed be a
  limiting part of the link. This suggests that
  investments in the reception system will improve
  the overall link quality.
• The use of two receiving antennas can reduce the
  rain margin allowance to achieve the required
  availability. For example, according to ITU
  recommendations, for two receive-antennas
  separated by 30km, the allowance to reach 99.9
  availability would be equivalent to a single
  antenna availability of 99.8.
• The iTV system is foreseen to be rate adaptive.
  The tool permits to assess the rate distribution
  that helps to configure the Hub according to the
  terminal distribution within the coverage area.
  The population analysis permits to verify the
  compromise in terms of population coverage and
  availability that has to be taken when selecting
  certain configurations for the data rates.
• An extension of the existing tool could be the
  implementation of the random access scheme and
  the assessment of the performance in a
  time-dependent dynamic manner instead of the
  photographic analysis done by this version.

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9. Discussion
Questions and Discussion
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• Thank you for your attention !